The present invention relates to a nail gun switch mechanism, and particularly to a nail gun switch mechanism for switching the nail gun operation in a sequential actuation mode, a contact actuation mode, or a holding actuation mode.
Actuating nails for a pneumatic nail gun generally can be divided into two kinds, one is the sequential actuation mode (or the restrictive mode) and the other is the contact actuation mode.
The sequential actuation mode means the operator firstly should set a safety slidable bar or a hitting base on the safety slidable bar contacting on a workpiece to push an upward movement of a trigger lever, and then press a trigger to bring the trigger lever to actuate a trigger valve. In this mode, if the operator wants to actuate again, he should release the trigger first, and then repeat the processes of pressing the trigger. If the operator disobeys the operating sequence, i.e. first pressing the trigger and then pressing the safety slidable bar or the hitting base of the safety slidable bar, the trigger lever in the trigger can not be brought to actuate the trigger valve and nails in the nail gun is held to be driven. Thus, no dangerous accidental shot happens when the safety slidable bar or the hitting base of the safety slidable bar is wrongly touched by somebody.
The contact actuation mode means the operator should first continuously press the trigger, and then move the safety slidable bar or the hitting base of the safety slidable bar on the workpiece to perform continuously contact hitting, which makes the trigger lever brought to upwardly move and actuates the trigger valve to continuous shot. In addition, the contact actuation mode also allows the operator first sets the safety slidable bar or the hitting base of the safety slidable bar on the workpiece to bring the trigger lever to upwardly move, and then individually or continuously presses the trigger to respectively actuate single or multiple nails for fastening the workpiece.
These two actuation modes are both used in a nail gun by utilizing a switch mechanism to realize switching of the sequential actuation mode and the contact actuation mode. As shown in U.S. Pub. No. 20050184120, a rotating rod is included in a contact safety assembly which is constructed to slide toward/away from a driver housing. The rotating rod includes a first shoulder or ledge and a second shoulder which is off-set from the first shoulder. The rod may be rotated in order to orientate the selected shoulder, to function as a step for a pivoting trigger assembly, which is constructed to contact a pneumatic valve, to initiate a fastening event in which a fastener is driven into a workpiece. The configuration of the rotating rod permits for selection between a contact actuation mode and a sequential actuation mode. However the mechanism can not permit a holding actuation mode, which makes the nail gun is easily to be wrongly actuated when the nail gun is set on something or is brought by somebody. Thus, accidentally dangerous shot easily happens.